CN111183373A

CN111183373A - Antireflection film, method for producing same, and polarizing plate with antireflection layer

Info

Publication number: CN111183373A
Application number: CN201880062537.7A
Authority: CN
Inventors: 宫本幸大; 山崎由佳; 金谷实; 梨木智刚
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2017-09-28
Filing date: 2018-08-10
Publication date: 2020-05-19
Anticipated expiration: 2038-08-10
Also published as: JP2019066515A; TW201919866A; KR102653072B1; JP7304129B2; CN111183373B; JP2023057085A; KR20220149625A; WO2019064969A1; KR20200037413A

Abstract

An antireflection film (100) of the present invention is provided with an antireflection layer (5) comprising a plurality of films having different refractive indices on one main surface of a transparent film substrate (1). The anti-reflective layer comprises a primer layer (50) in contact with the transparent film substrate. The primer layer has an argon content of 0.5 atomic% or less. The primer layer (50) is, for example, a silicon oxide layer. The moisture permeability of the antireflection film is preferably 1g/m²24h or less. The polarizing plate (101) with an antireflection layer is provided with the antireflection film (100) on a polarizer (8).

Description

Antireflection film, method for producing same, and polarizing plate with antireflection layer

Technical Field

The present invention relates to an antireflection film including an antireflection layer including a plurality of films on a transparent film, and a method for producing the antireflection film.

Background

An antireflection film is used on the viewing side surface of an image display device such as a liquid crystal display or an organic EL (Electroluminescence) display in order to prevent deterioration of image quality due to reflection of outside light or reflection of an image, to improve contrast, or the like. The antireflection film is provided with an antireflection layer comprising a laminate of a plurality of films having different refractive indices on a transparent film.

As one example of the antireflection film, a polarizing plate with an antireflection layer is cited. An antireflection film is attached to the surface of the polarizing plate, or an antireflection film as a protective film is attached to the surface of the polarizer, thereby obtaining an antireflection layer-equipped polarizing plate. An antireflection layer may be formed on the surface of the polarizing plate.

Various attempts to provide an antireflection layer with a water vapor barrier property are known. For example, in patent document 1, ITO and SiO are formed by a sputtering method₂In a sequence ofThe films are stacked, and a silicon oxide film is formed thereon by a plasma CVD (chemical vapor deposition) method, thereby improving water vapor barrier properties. In patent document 2, a silicon nitride film having a high refractive index is provided to reduce the moisture permeability of the antireflection film. Patent document 3 describes that the outermost layer (the layer farthest from the film base) of the antireflection layer has a high correlation between density and moisture permeability.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2000-338305

Patent document 2: japanese patent laid-open publication No. 2003-139907

Patent document 3: japanese laid-open patent publication No. 2009-109850

Disclosure of Invention

Problems to be solved by the invention

By providing an antireflection layer having a water vapor barrier property on the surface of the polarizing plate, deterioration of the polarizing plate in a high humidity environment is suppressed, and durability is improved. In recent years, further high humidity durability has been demanded for displays, and an antireflection film (low moisture permeability) having a higher water vapor barrier property than before has been demanded. In view of the above circumstances, an object of the present invention is to provide an antireflection film having excellent water vapor barrier properties.

Means for solving the problems

The antireflection film of the present invention includes an antireflection layer including a plurality of films having different refractive indices on one main surface of a transparent film substrate. The antireflective layer comprises a primer layer in contact with the transparent film substrate. Preferably, the high refractive index layer and the low refractive index layer are alternately stacked on the primer layer. The moisture permeability of the antireflection film is preferably 1g/m²24h or less.

The argon content of the primer layer is preferably 0.01 to 0.5 atomic% or less. The primer layer is preferably a silicon oxide layer. The primer layer is preferably formed by a sputtering method. The thin film on the primer layer constituting the antireflection layer is also preferably formed by a sputtering method.

The present invention also relates to a polarizing plate with an antireflection layer, which comprises the antireflection film on one surface of a polarizer.

ADVANTAGEOUS EFFECTS OF INVENTION

The antireflection film of the present invention has excellent gas barrier properties, and a display having an antireflection layer-equipped polarizing plate with a low moisture permeability on the surface thereof has a small amount of moisture entering the polarizer even when exposed to a high-humidity environment, and therefore can suppress deterioration of the polarizer.

Drawings

Fig. 1 is a cross-sectional view schematically showing one embodiment of an antireflection film.

Fig. 2 is a cross-sectional view schematically showing one embodiment of a polarizing plate with an antireflection layer.

Detailed Description

[ constitution of antireflection film ]

Fig. 1 is a cross-sectional view schematically showing a structure of an antireflection film according to an embodiment. The antireflection film 100 includes an antireflection layer 5 so as to be in contact with the transparent film substrate 1. The antireflection layer is a laminate of 2 or more thin films, and the antireflection layer 5 shown in fig. 1 is provided with a primer layer 50 on the surface in contact with the transparent film substrate 1, and high

refractive index layers

51, 53 and low

refractive index layers

52, 54 are alternately laminated thereon.

The moisture permeability of the antireflection layer 5 is preferably 1g/m²24h or less, more preferably 0.7g/m²24h or less, more preferably 0.5g/m²24h or less. By reducing the moisture permeability of the antireflection layer, the penetration of moisture can be prevented, and deterioration of a polarizer or the like due to moisture can be suppressed. As described in detail below, when the amount of argon contained in the primer layer is small, the moisture permeability of the antireflection film tends to be low.

< transparent film substrate >

The transparent film substrate 1 includes a flexible transparent film 10. The hard coat layer 11 is preferably provided on the side of the transparent film 10 on which the antireflection layer 5 is formed.

(transparent film)

The visible light transmittance of the transparent film 10 is preferably 80% or more, more preferably 90% or more. The thickness of the transparent film 10 is not particularly limited, but is preferably about 5 to 300 μm, more preferably 10 to 250 μm, and still more preferably 20 to 200 μm from the viewpoints of strength, workability such as handling properties, and thin layer properties.

Examples of the resin material constituting the transparent film 10 include thermoplastic resins having excellent transparency, mechanical strength, and thermal stability. Specific examples of such thermoplastic resins include: cellulose resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

(hard coating)

By providing the hard coat layer 11 on the surface of the transparent film 10, mechanical properties such as hardness and elastic modulus of the antireflection film can be improved. The hard coat layer 11 preferably has a high surface hardness and excellent scratch resistance. The hard coat layer 11 can be formed by, for example, applying a solution containing a curable resin on the transparent film 10.

Examples of the curable resin include: a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, or the like. Examples of the curable resin include: polyester-based, acrylic-based, urethane-based, acrylic-based urethane-based, amide-based, silicone-based, silicate-based, epoxy-based, melamine-based, oxetane-based, acrylic-based urethane-based, and the like. One or more of these curable resins may be appropriately selected and used.

Among these, acrylic resins, acrylic urethane resins, and epoxy resins are preferable from the viewpoint of high hardness, ultraviolet-curable properties, and excellent productivity, and among these, acrylic urethane resins are preferable. The ultraviolet-curable resin includes ultraviolet-curable monomers, oligomers, polymers, and the like. The ultraviolet curable resin preferably used includes, for example, those having an ultraviolet polymerizable functional group, and among them, those containing, as a component, an acrylic monomer or oligomer having 2 or more, particularly 3 to 6 functional groups.

The hard coat layer 11 may have an anti-glare property in order to provide the anti-reflection film with an anti-glare property and an anti-glare property. Examples of the hard-coat antiglare layer include those having fine particles dispersed in the curable resin matrix. As the fine particles dispersed in the resin matrix, there can be used, without particular limitation: fine particles of various metal oxides such as silica, alumina, titanium oxide, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc., fine glass particles, crosslinked or uncrosslinked organic fine particles comprising various transparent polymers such as polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate, etc., fine silicone particles, etc., have transparency.

The hard coat layer 11 can be formed by, for example, applying a solution containing a curable resin on the transparent film 10. In the solution for forming the hard coat layer, an ultraviolet polymerization initiator is preferably compounded. In order to form the antiglare hard coat layer containing fine particles, a solution containing the fine particles in addition to the curable resin is preferably applied to the transparent film. The solution may also contain additives such as leveling agents, thixotropic agents, antistatic agents, and the like.

The thickness of the hard coat layer 11 is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more, in order to achieve high hardness. In view of ease of formation by coating, the thickness of the hard coat layer is preferably 15 μm or less, more preferably 10 μm or less.

The surface of the transparent film substrate 1 on the side where the antireflection layer 5 is formed preferably has an arithmetic average roughness Ra of 1.0nm or less. When the hard coat layer 11 is formed on the transparent film 10, the arithmetic average roughness Ra of the hard coat layer 11 is the arithmetic average roughness of the surface of the transparent film 10 on the side where the antireflection layer 5 is formed. The arithmetic average roughness Ra was determined from an observation image of 1 μm square obtained using an Atomic Force Microscope (AFM).

When the hard coat layer 11 is formed by coating as described above, the arithmetic mean roughness of the surface of the transparent film substrate 1 can be reduced. If the surface of the transparent film substrate 1 is smooth, defects such as pinholes in the antireflection layer 5 can be suppressed, and thus an antireflection film having lower moisture permeability can be obtained.

(surface treatment)

The surface of the transparent film base 1 may be subjected to surface modification treatment such as corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, treatment with a coupling agent, and the like for the purpose of improving adhesion to the antireflection layer 5.

< anti-reflection layer >

An antireflection film is formed by providing an antireflection layer 5 on a transparent film substrate 1. The antireflection layer 5 has a primer layer 50 on the surface in contact with the transparent film substrate 1, and a high refractive index layer and a low refractive index layer thereon. In general, the antireflection layer adjusts the optical film thickness (product of refractive index and thickness) of the thin film so that the inverted phases of incident light and reflected light cancel each other out. By providing a multilayer laminate of a plurality of thin films having different refractive indices as the antireflection layer, the reflectance can be reduced in a wavelength range in a wide band region of visible light.

Examples of the material of the thin film constituting the antireflection layer 5 include metal oxides, nitrides, and fluorides. As a material of the primer layer 50, silicon oxide is preferable. The content of argon in the film of the primer layer 50 is 0.5 atomic% or less. The low refractive index layers 52 and 54 have a refractive index of, for example, 1.6 or less, preferably 1.5 or less. As the low refractive index material, there can be mentioned: silicon oxide, magnesium fluoride, and the like. The high refractive index layers 51 and 53 have a refractive index of, for example, 1.9 or more, preferably 2.0 or more. As the high refractive index material, there can be mentioned: titanium oxide, niobium oxide, zirconium oxide, Indium Tin Oxide (ITO), antimony doped tin oxide (ATO), and the like. In addition to the low refractive index layer and the high refractive index layer, a thin film containing, for example, titanium oxide or a mixture of the low refractive index material and the high refractive index material may be provided as the medium refractive index layer having a refractive index of about 1.6 to 1.9.

The method for forming the thin film constituting the antireflection layer 5 is not particularly limited, and any of a wet coating method and a dry coating method may be used. In order to form a thin film having a uniform thickness, dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam deposition are preferable. Among them, the sputtering method is preferable in that a dense film having excellent uniformity of film thickness and high gas barrier properties can be easily formed. In particular, in order to obtain an antireflection film having low moisture permeability, it is preferable to form a silicon oxide film as the primer layer 50 by a sputtering method.

In the sputtering method, a plurality of thin films can be continuously formed while a long film substrate is conveyed in one direction (longitudinal direction) by a roll-to-roll (roll) method, and therefore, the productivity of the antireflection film can be improved. In order to improve the productivity of the antireflection film, it is preferable to form all the thin films constituting the antireflection layer 5 by sputtering. In the sputtering method, a film is formed while introducing an inert gas such as argon and, if necessary, a reactive gas such as oxygen into a chamber.

The oxide layer can be formed by a sputtering method by any of a method using an oxide target and reactive sputtering using a metal target. In order to form an insulating oxide such as a silicon oxide using an oxide target, RF (radio frequency) discharge is required. In order to form a metal oxide film at a high rate, reactive DC (direct current) sputtering using a metal target is preferable.

(primer layer)

The amount of argon in the film of the primer layer 50 is 0.5 atomic% or less, preferably 0.4 atomic% or less. When the amount of argon in the sputtered film is 0.5 atomic% or less, the moisture permeability tends to decrease, and the water vapor barrier property of the antireflection film tends to improve. The reason why the antireflection layer has low moisture permeability by reducing the amount of argon in the film of the primer layer is not clear, but 1 factor is considered to be related to the following cases: if argon having a large atomic radius is present in the primer layer, a channel of a gas such as water vapor is easily formed in the primer layer and the thin film formed thereon.

As described above, in the sputtering film formation, argon is used as a process gas, and high-energy argon is made to collide against a target to cause a material to be ejected from the target, and sputtering particles ejected from the target are made to adhere to a base material, thereby forming a film. Inert gases such as argon generally do not participate in film formation, but ionized argon has high reactivity, and therefore a part of argon as a process gas is inevitably introduced into a film during sputter film formation.

Since argon, which is a rare gas, has a larger atomic diameter than silicon and oxygen, argon introduced into the film may be a factor that prevents formation of an Si — O bond network structure of silicon oxide and forms voids at an atomic level. If voids due to the mixing of argon are formed in the primer layer 50 that is initially formed in contact with the film substrate 1, then when the high refractive index layers 51, 53 and the low refractive index layers 52, 54 are sputter-formed thereon, the voids tend to grow in a columnar shape in the thickness direction, and become channels for gas such as water vapor, and the moisture permeability increases. In contrast, it is considered that the amount of argon introduced into the primer layer 50 is reduced to suppress the generation of voids which serve as channels for water vapor, thereby forming a low moisture-permeable antireflection layer having excellent water vapor barrier properties.

The smaller the amount of argon contained in the primer layer 50, the better, but a film obtained by sputtering film formation using argon as a process gas usually contains 0.01 atomic% or more of argon. The argon content in the primer layer may also be 0.05 atomic% or more, or 0.1 atomic% or more. The amount of argon in the film was measured by Rutherford Backscattering (RBS) method, and the amount of argon in the silicon oxide film was calculated by setting the total content of silicon, oxygen and argon to 100 atomic%.

As a method for suppressing the incorporation of argon into the primer layer, it is preferable to increase the mean free path and promote the scattering of argon by reducing the process pressure during film formation. The process pressure for forming the primer layer 50 is preferably about 0.05 to 2Pa, more preferably about 0.07 to 1Pa, still more preferably 0.1 to 0.5Pa, and particularly preferably 0.1 to 0.3 Pa. The amount of oxygen introduced into the film forming chamber during the formation of the primer layer 50 is preferably about 0.1 to 10%, more preferably about 0.5 to 5%, and still more preferably about 1 to 3% of the amount of argon introduced in terms of volume ratio.

Argon and oxygen are introduced during sputter deposition to promote formation of a Si — O bond network structure, thereby suppressing argon from being mixed into the film. On the other hand, in order to improve the adhesion between the film base 1 and the antireflection layer 5, the primer layer 50 is preferably an oxygen content less than the stoichiometric composition. The thickness of the primer layer 50 may be, for example, about 1 to 10nm as long as the transparency of the transparent film substrate 1 is not impaired.

(film on primer layer)

The type of the thin film formed on the primer layer 50 is not particularly limited. From the viewpoint of reducing the reflectance over a wide wavelength range, it is preferable to alternately provide the high refractive index layer and the low refractive index layer. The film 54 provided as the outermost layer (layer farthest from the film base 1) of the antireflection layer 5 is preferably a low refractive index layer in order to reduce reflection at the air interface. As described above, the material of the low refractive index layer and the high refractive index layer is preferably an oxide. Among them, niobium oxide (Nb) as a high refractive index layer is preferable₂O₅)

Thin films

51, 53, and silicon oxide (SiO) as a low refractive index layer₂) The

films

52, 54 are alternately laminated.

The sputtering deposition of the low refractive index layer and the high refractive index layer on the primer layer is preferably performed in such a manner that the deposition mode becomes the transition region. For example, in a plasma emission monitoring method (PEM method) in which the plasma emission intensity of discharge is detected to control the amount of gas introduced into the film forming chamber, feedback of the amount of oxygen introduced is performed based on the plasma emission intensity. By controlling the oxygen introduction amount by the PEM, the film formation rate can be kept constant when a thin film is formed by a roll-to-roll method, and therefore, the film thickness of the thin film becomes uniform, and an antireflection film having excellent antireflection characteristics can be obtained. By providing a plurality of plasma emission measurement points in the width direction and independently controlling the oxygen introduction amount by the PEM, uniformity of the quality in the width direction can be improved.

< additional layer on antireflection layer >

The antireflection film may have an additional functional layer provided on the surface of the antireflection layer 5. Since the antireflection film is disposed on the outermost surface of the display, it is easily contaminated by external environment (fingerprint, hand dirt, dust)Etc.). In particular SiO, which is arranged on the outermost surface of the anti-reflection layer 5₂The low refractive index layer 54 has good wettability, and contaminants such as fingerprints and hand stains are easily attached thereto. An anti-fouling layer (not shown) may be provided on the anti-reflection layer to facilitate prevention of contamination from the external environment, removal of attached contaminants, and the like.

The antifouling layer preferably has a small refractive index difference from the low refractive index layer 54 on the outermost surface of the antireflection layer 5. The refractive index of the antifouling layer is preferably 1.6 or less, and more preferably 1.55 or less. The material of the antifouling layer is preferably a fluorine-containing silane compound, a fluorine-containing organic compound, or the like. The antifouling layer can be formed by a wet method such as a reverse coating method, a die coating method, or a gravure coating method, a dry method such as a CVD method, or the like. The thickness of the antifouling layer is usually about 1 to 100nm, preferably 2 to 50nm, and more preferably 3 to 30 nm.

[ polarizing plate with antireflection layer ]

The antireflection film is disposed on the surface of a display, for example. As shown in fig. 2, an antireflection layer-equipped polarizing plate in which an antireflection film 100 and a polarizer 8 are laminated may be attached to the surface of the display. In the antireflection layer-equipped polarizing plate 101 shown in fig. 2, one surface of a polarizer 8 is bonded to the main surface of the transparent film substrate 1 opposite to the surface on which the antireflection layer 5 is formed. A transparent film 9 is bonded to the other surface of the polarizer 8. In this configuration, the film substrate 1 has both a function as a substrate for forming the antireflection layer 5 and a function as a protective film for the polarizer 8. In the production of the antireflection film, the polarizing plate may be produced by laminating the polarizer 8 to the film base 1, and the antireflection layer 5 may be formed on the film base 1 of the polarizing plate.

Examples of the polarizing material 8 include: and polyene-based oriented films obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and partially saponified ethylene-vinyl acetate copolymer-based films, and polyvinyl alcohol-dehydrated products and polyvinyl chloride-desalted products.

Among them, a polyvinyl alcohol (PVA) -based polarizing material in which a dichroic material such as iodine or a dichroic dye is adsorbed to a polyvinyl alcohol-based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol and oriented in a specific direction is preferable in terms of having a high degree of polarization. For example, a PVA-based polarizer can be obtained by subjecting a polyvinyl alcohol-based film to iodine dyeing and stretching. A thin polarizer having a thickness of 10 μm or less may be used as the PVA polarizer. Examples of the thin polarizing film include thin polarizing films described in japanese patent laid-open nos. 51-069644, 2000-338329, WO2010/100917, 4691205, 4751481, and the like. Such a thin polarizer can be obtained, for example, by a manufacturing method including the steps of: stretching the PVA-based resin layer and the stretching resin base material in a state of being laminated; and a step of performing iodine dyeing.

As the transparent film 9, the same material as that described above as the material of the transparent film 10 is preferably used. The material of the transparent film 9 may be the same as or different from that of the transparent film 10.

For the adhesion of the polarizer and the transparent film, an adhesive is preferably used. As the adhesive, those using as a base polymer an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, polyvinyl alcohol, polyvinyl ether, a vinyl acetate/vinyl chloride copolymer, a modified polyolefin, an epoxy polymer, a fluorine polymer, a rubber polymer, and the like can be appropriately selected. For bonding the PVA-based polarizer, a polyvinyl alcohol-based adhesive is preferably used.

The antireflection film and the antireflection layer-equipped polarizing plate of the present invention can be used for displays such as liquid crystal display devices and organic EL display devices. Especially in the case of use as the outermost layer of a display, it contributes to the improvement of the visibility of the display obtained by the reflection prevention. By providing the low moisture-permeable antireflection film 100 having the predetermined primer layer 50 on the surface of the polarizer 8, the penetration of moisture into the polarizer 8 from the external environment can be suppressed. Therefore, even when the display is exposed to a high humidity environment, yellowing and discoloration due to deterioration of the polarizer are less likely to occur, and changes in display characteristics can be suppressed.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[ production of film with hard coat ]

A composition for forming a hard coat layer was prepared by mixing 100 parts by weight (solid content) of an ultraviolet-curable acrylic resin (trade name: GRANDIC PC-1070; refractive index: 1.52, manufactured by DIC Co., Ltd.) and 50 parts by weight of nano silica particles as an inorganic filler. This composition was applied to one surface of a cellulose triacetate film (trade name "FUJITAC" manufactured by FUJIFILM) having a thickness of 100 μm so that the dried thickness became 5 μm, and dried at 80 ℃ for 3 minutes. Thereafter, the cumulative light quantity was irradiated with 200mJ/cm using a high-pressure mercury lamp²The ultraviolet ray of (3) cures the coating layer to form a hard coating layer.

[ example 1]

The cellulose triacetate film with the hard coating layer formed thereon was introduced into a roll-to-roll sputtering film-forming apparatus, and after bombardment treatment (plasma treatment with argon (Ar)) was performed on the antiglare hard coating layer-forming surface while moving the film, a 3.5nm silicon oxide layer was formed as a primer layer, and 12nm Nb was sequentially formed thereon₂O₅Layer, 28nm SiO₂Layer, 100nm Nb₂O₅Layer and 85nm SiO₂And (3) forming an antireflection film.

The bombardment treatment was carried out under a pressure of 1.5 Pa. The silicon oxide layer as the primer layer was formed by applying 0.5W/cm to a Si target at a substrate temperature of-8 deg.C, an argon flow rate of 300sccm, an oxygen flow rate of 4.5sccm, and a pressure of 0.2Pa²The film is formed by DC sputtering with the electric power of (1). SiO 2₂The layer was formed using an Si target, Nb₂O₅The film was formed using an Nb target at a substrate temperature of-8 ℃, an argon flow of 400sccm, and a pressure of 0.25 Pa. In SiO₂Film formation of layer and Nb₂O₅During the formation of the layer, the amount of oxygen introduced is adjusted by plasma emission detection (PEM) control so as to maintain the transition region in the film formation mode。

Example 2 and comparative example 1

The sputtering deposition conditions for the primer layer were changed as shown in table 1, and in comparative example 1, the primer layer was deposited without introducing oxygen. In comparative example 1, the flow rate of argon was changed to 1200sccm and the pressure was changed to 0.45 Pa. Except for this, an antireflection film was produced in the same manner as in example 1.

[ evaluation of antireflection film ]

(moisture permeability)

According to JIS K7129: 2008, appendix B, the moisture permeability of the antireflection film was measured in an atmosphere at a temperature of 40 ℃ and a humidity of 90% RH. Since the moisture permeability of the film base is sufficiently higher than that of the antireflection layer, the moisture permeability of the antireflection film as a whole is considered to be equivalent to that of the antireflection layer.

(film Density and composition of film)

The film density and composition of the thin film constituting the antireflection layer were measured by Rutherford Backscattering (RBS) method. In the calculation of the film density, the film thickness obtained by Transmission Electron Microscope (TEM) observation of the cross section was used, and the elemental composition was calculated based on the elemental composition at the center of the film thickness of each thin film, with the total content of metal (silicon or niobium), oxygen, and argon being 100 atomic%.

[ production of polarizing plate with antireflection layer and evaluation of durability ]

The antireflection films of examples and comparative examples were bonded to one surface of a polarizer, and a transparent film having a thickness of 30 μm and containing a modified acrylic polymer having a lactone ring structure was bonded to the other surface of the polarizer, thereby producing an antireflection layer-equipped polarizing plate. As the polarizer, a PVA-based polarizer obtained by iodine-dyeing a polyvinyl alcohol film having an average polymerization degree of 2700 and a thickness of 75 μm and stretching the film 6-fold was used. The PVA-based polarizer and the transparent film were bonded to each other with an adhesive containing an aqueous solution in a weight ratio of 3: 1 comprises a polyvinyl alcohol resin having an acetoacetyl group (average polymerization degree of 1200, saponification degree of 98.5 mol%, acetoacetylation degree of 5 mol%) and methylolmelamine.

The obtained antireflection layer-attached polarizing plate was put into a constant temperature and humidity chamber having a temperature of 60 ℃ and a RH of 90% and taken out after 72 hours. A commercially available polarizing plate was placed on a backlight device to determine the chromaticity b of transmitted light^*Before and after the heating and humidifying test, the variation amount Delta b^*。

The film characteristics of each layer of the anti-reflection layers of examples and comparative examples, the film formation conditions of the primer layer, the moisture permeability of the anti-reflection film, and the transmitted light b before and after the heat and humidity test of the anti-reflection layer-equipped polarizing plate^*The amount of change in (c) is shown in table 1.

[ Table 1]

As shown in table 1, the antireflection films of examples 1 and 2 have a smaller moisture permeability than comparative example 1, and the polarizing plate with an antireflection layer has a smaller chromaticity difference before and after the heating and humidifying test, and exhibits excellent durability. With respect to SiO as the outermost layer₂No clear difference was observed in the film density of the layer (film thickness: 85nm) in the examples and comparative examples.

Nb₂O₅With SiO₂Compared with the moisture permeability, therefore, the material has higher moisture permeability in SiO₂And Nb₂O₅In the alternate laminate film of (2), SiO₂The moisture permeability of the film is limited, and the moisture permeability is mainly determined by SiO₂The properties of the film. In comparative example 1, since Nb₂O₅Since the film forming pressure of the layer was small, Nb was observed in comparison with examples 1 and 2₂O₅The film density of the layer tends to be small, but Nb is considered to be₂O₅The difference in film density of the layers hardly affects the change in moisture permeability.

Examples 1 and 2 were different from comparative example 1 in the conditions for forming the primer layer, and examples 1 and 2, in which the film was formed with a low argon introduction amount (low pressure) while introducing oxygen, were different in the argon amount in the film from comparative example 1. From the results, it is considered that in the examples, the water vapor barrier property of the antireflection film was improved (moisture permeability was reduced) by reducing the amount of argon contained in the primer layer, and the durability of the antireflection layer-equipped polarizing plate was improved.

Description of the reference numerals

1 transparent film substrate

10 transparent film

11 hard coating

5 anti-reflection layer

50 primer layer

51. 52, 53, 54 film

8 polarizing element

9 transparent film

100 anti-reflection film

101 polarizing plate with anti-reflection layer

Claims

1. An antireflection film comprising an antireflection layer including a plurality of films having different refractive indices on one main surface of a transparent film substrate,

the antireflective layer comprises a primer layer in contact with the transparent film substrate,

the content of argon in the primer layer is less than 0.01-0.5 atomic%.

2. The antireflection film as claimed in claim 1, wherein the primer layer is a silicon oxide layer.

3. The antireflection film according to claim 2, wherein the antireflection layer comprises a high refractive index layer and a low refractive index layer alternately on the primer layer.

4. The antireflection film as claimed in claim 3, wherein the high refractive index layer is a niobium oxide layer, the low refractive index layer is a silicon oxide layer, and an oxygen amount of silicon oxide of the primer layer is smaller than an oxygen amount of silicon oxide of the low refractive index layer.

5. The antireflection film as claimed in any one of claims 1 to 4, which has a moisture permeability of 1g/m²24h or less.

6. The antireflection film according to any one of claims 1 to 5, wherein the transparent film substrate is provided with a hard coat layer on a surface in contact with the primer layer.

7. A polarizing plate with an antireflection layer, comprising the antireflection film according to any one of claims 1 to 6 on one surface of a polarizer.

8. A method for producing an antireflection film according to any one of claims 1 to 6,

the primer layer is formed by sputtering.

9. The method of manufacturing an antireflection film according to claim 8, wherein all the thin films constituting the antireflection layer are formed by a sputtering method.